Cooling device for stators of electric machines



March 17, 1925. 1,529,993

.P. EHRMANN COOLING DEVICE FOR STATORS OF ELECTRIC MACHINES Patented'Mar. 17, 1925.

PAUL- EHRMANN, 0F PARIS, FRANCE.

COOLING DEVICE FOR STATORS OF' ELECTRIC MACHINES.

Original application filed March 18, 1921, Serial No. 456,136.

Divided and this application filed April 4,1922. Serial No. 549,509.

To all whom it may concern.

Be it known that I, PAUL Enmmx N, (1111b zen of the Republic of France,residing at Paris, France, have invented certain new and usefulImprovements in Cooling Devices for Stators of Electric Machines (forwhich I have obtained a patent in France under No. 497,839 on anapplication-filed April 4, 191 a patent in Switzerland under No. 91,694on an application filed March 17, 1920, a patent in Belgium under No.286,321 on an application filed April 21, 1920, two patents in GreatBritain under Nos. 142,828 and 162,281 on an application filed on May 4,1920, and subsequently divided, and for which I have also madeapplication for patent in Germany on April 15, 1920), of which thefollowing is a specification.

My invention relates to improvements applied to cooling devices for'thestators of electrical machines such as describedin my application, Ser.No. 456,136 filed March 18, 1921, of which this is a division and itsobject is to provide laminated masses presenting considerable coolingsurface.

The invention has also for its object the 'utilization for obtainingcooling fins of those portions of sheet metal plates which usuallyconstitute the normal waste in cutting the plates.

The laminated masses for the stators of electrical machines according tomy invention are characterized essentially by the external contour ofthe plates presenting a configuration mainly circular but provided withprojections intended to constitute the cooling fins, the successiveplates or groups of plates being staggered relatively to one another soas to provide air circulation channels between the cooling fins thesurfaces of which present a considerable exposed area.

The preferred form of the invention is illustrated by way of example onthe accompanying drawings, in which Fig. 1 shows a plate with fourcooling fins entering into the constitution of a laminated massaccording to my invention.

Fig. 2 is an elevation of a laminated mass for a stator of an electricmachine, obtained by the superposition of sheets according to that shownin Fig. 1.

Fig. 3 is a section along the line 3-3 of Fi 2.

3 plate or sheet used for making up a laminated mass for a stator of anelectric machine according to my invention is shown in Fig. 1. Thissheet a has an external contour mainly circular but provided with fourprojecting cooling fins Z situated at the ends of two diameters mutuallyat right angles, each of said fins projecting from the circular contour.

To make these plates, the following method may be pursued withadvantage: A polygon of a number of sides equal to the number of fins, asquare for example, is drawn at the external periphery of the plate inthis case square plates are selected. The plate is cut circular withinsuch square leaving at each angle of the square a cooling fin betweenthe sides of the square and the circumference of the plate. Thus wastein cutting is reduced as much as possible.

To produce a laminated mass for a stator of an electric machine bymeans'oi' the above described plates, it sullices to super-pose theplates alternately in the positions 3/ and (Fig. 1). Thus a stator(Figs. 2 and 3) can be obtained provided with eight coolin elements oflarge surface, the thickness oi the cooling channels being equal to thethickness of the fins Z.

The circulation of the cooling air in the above stator is effected asfollows:

Air under pressure obtained from the our rent of ventilating air of theelectric machine enters the interior of such machine, as indicated at cat the bottom of Fig. 3. The current of air entering the region 0 isdivided into two elementary currents which can escape through theopenings b 01 the structure (Figs. 2 and 3) after having completelyswept the lateral surfaces of all the fins Z carried by the laminatedmass in one part or another in the vicinity of the region of entry 0.

The above described arrangement obviouslypermits various modificationswithin the scope of this invention.

In particular, the air admission openings 0 and outlets b may be locatedand grouped at will, as well as the supply and evacuation channels forthe air in the structure of stators of electric machines. Instead ofprovid ing four air-admission openings 0 and four outlet openings 12, inthe case of low powered machines only two admission openings 0 and twooutlet openings 1) may be provided.

Likewise, the angle a (Fig. 1) may be varied, which enables laminatedmasses to be n iade by meansrof plates-identicallyalike viously eachplate, a, can be replaced by a group of similar plates exactlysuperposed. It suflices then, in order to make the laminated niassiorestator of an electric,- machine, to superpose such groups of; plates aalternately in the positions 1 and a, as above described.

The inveutlon ithus enables laminated ma s :f ';-s o.1t ;of electricmachines t large coolingsurfaces to ;be obtaineclata ery slightlyincreased net cost.

Claims: V,

1. In a stator for electric machines; the combination 5 of plates of.CjillClllfil'ejfiXllfiIDfil contour having. lug ,pirigjectiug atl'interrals beyond the circular contour and constituting coolingfins,:the said plates being stacked up in a certain ;1 1u1 n ber.ofipositions OfiSet relative to each other, thessaid cooling finsthusforminga ,plurality of sets ,parallelcto the axis ;.of the stator.each; "set being acornposed: of a plurality of; fins, thersets beingseparated from each other by d rect-spaces utilized as thesupporting-.surtfaces got the laminated core, ,a i'ra1ne en closing allthe saidplates ,prowidingabutments, :Eorgthe support of; the (saidplatte s 1-; air inlet conduits provided in --,t he I s aid i iirame;for guiding t cur? rents of airparallelto t h-e axis of the vstator,eachio f the said iai ieurrents. (being divide combination of. plates of,circular. external licontour having lugs proyecting' at intervalsbeyond the circular contour andconstituting cooling fins, thesaid platesbeing stacked in a, certainnumberof positionsroffset relative V to eachother, .the said cooling fins thus forminga plui'ality .ofaset-sparallel to the aj-pluralityoffins-separated iromzeach other by, freespaces-Y utilized as supporting ;tac.es oiithe, laminated core a framecnclosinggall the said plates providingabutinents for the supportof saidplates,.air inlet conduits gprovided in the said frame guiding thecurrents of; air parallel atothe axis of the stator,-,each of; the saidair cur-rents circulating between two i sets of ;;successive fins andbeing divided into elementary currents ,passing through the freespaces"providedbetween the fins of the said two sets: and, sweepingthe-said fins over their entire suittace dischargeopenings for the hot,air, being providedf ,in the said iran eiadj acent the said freespaces,

I In testimonywhereof, I afli xed, any, signa; ture.

PAUL ,IEHRMANN.

